who worked under Sir J. J. Thomson at Cambridge University (1895–98). He then took up a professorship at McGill University, Canada, and collaborated with Frederick Soddy in studying radioactivity. In 1899 he discovered alpha particles and beta particles, followed by the discovery of gamma radiation the following year. In 1902–03, with Soddy, he announced that radioactive decay involves a series of transformations. He moved to Manchester University in 1907 and there, with Hans Geiger and Ernest Marsden, devised the alpha-particle scattering experiment that led in 1911 to the discovery of the atomic nucleus After moving to Cambridge in 1919 he achieved the artificial splitting of light atoms. In 1908 he was awarded the Nobel Prize for chemistry.